The South River is a 10-mile-long (16 km)[1] tributary of the Chesapeake Bay in Anne Arundel County, Maryland in the United States.

From its headwaters in western Anne Arundel County in Crofton, the river enters the Chesapeake Bay south of the historic port city of Annapolis, hence the name South River.

Some of the creeks on its north shore drain highly developed portions of Annapolis, especially Church Creek, which drains much of the Parole and Annapolis Harbour shopping centers.

A bridge carrying US 50 crosses its upper tidal reaches.

It was located between Almshouse Creek (named because London Town's only surviving house was used as the county almshouse until 1965) and Glebe Bay, and across the river from Ferry Point (before the bridges were built, ferries to Annapolis ran between London Town and Ferry Point).